The document is concerned with the choice and definition of ground motion parameters for maps used in model building codes. Such maps specify, for any location, parameters from which earthquake-representing forces are evaluated and used for design and analysis of structures and non-structural components. The document sets forth recommendations concerning the preparation of future ground motion hazard maps, and identifies requirements for the research needed to be able to prepare and utilize these maps. The focus of the report is upon what quantities -- each a simple descriptor of some significant aspect of ground motion -- should be mapped. The report also provides background information concerning the evolution of hazard maps for building codes and the associated needs for ground motion parameters maps, and discusses current hazard mapping issues. The use of these maps as the starting point for design and analysis is presented. The problem of bringing in the effects of local soil and topographic conditions, and research efforts necessary if the recommended maps and analysis procedures are to come into general use by the end of the century are also covered.